A conventional method and device of this type are described in German Patent Application No. 195 24 939, which provides a controller for a brake system in which braking force is exerted upon the wheel brakes beyond the actual driver input in certain operating situations detected on the basis of the driver's braking intention. One of these operating situations is one in which a hazardous situation can be concluded from the driver's response. To detect this situation, the way in which the driver presses the brake operating element is analyzed. If he presses the element very quickly, which is determined for example by a variation in brake system admission pressure, pressure builds up beyond the driver input. If the analyzed quantity exceeds a specific threshold value (trigger threshold), the automatic braking action (i.e., increased buildup of braking force) takes place. The trigger threshold is varied on the basis of specific performance quantities, thereby reducing the trigger threshold, which means that increased braking force buildup triggering becomes more sensitive as the potential danger increases. The performance quantities described above are braking system admission pressure, vehicle velocity, rate of vehicle rotation, transverse vehicle acceleration, longitudinal vehicle acceleration, variation of the steering angle, engine power output, and/or the brake pressure requested by a vehicle dynamics controller. Since too sensitive of a brake assistant, which could trigger an automatic braking action even in non-hazardous situations, is not desired, special attention must be paid to determining the trigger threshold.
One of the objects of the present invention is to provide a means (e.g., an arrangement) for very reliably detecting potential danger and making the brake assistant response more sensitive in the event of a perceived danger.
SAE paper No. 961010, entitled “Adaptive Cruise Control, System Aspects and Development Trends” by Hermann Winner, Stefan Witte, Werner Uhler, and Bernd Lichtenberg describes an adaptive cruise control system that is equipped with sensors for detecting obstacles in front of the vehicle. The adaptive cruise control system detects the distance to the obstacles in front of the vehicle as well as their relative velocity. Based on additional sensor signals, it selects the closest obstacle and, if necessary, reduces the road speed of the vehicle equipped with the adaptive cruise control system.